Circuit control device



25, 1953 H. 8. JAMES 2,650,328

' CIRCUIT CONTROL DEVICE Filed Nov. 16, 1950 3 Sheets-Sheet 1 WITNESSES: INVENTOR Homer B.Jomes.

ATTORNEY 1953 H. B. JAMES 2,650,328

CIRCUIT CONTROL DEVICE Filed Nov. 16, 1950 3 Sheets-Sheet 2 Fig.3.

WITNESSES: INVENTOR 7 HomerB.Jumes ATTORN EY Aug. 25, 1953 H. B. JAMES ,328

CIRCUIT CONTROL DEVICE Filed Nov. 16, 1950 s Sheets-Sheet?) WITNESSES: I INVENTOR Homer B.Jum

ATTORNEY Patented Aug. 25,1953

CIRCUIT CONTROL DEVICE Homer B. James, Lima, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 16, 1950, Serial No. 196,041

7 Claims.

My invention relates, generally, to circuit breaker control systems and, more particularly, to systems for controlling the operation of. electromagnetically operated circuit breakers. or contactors.

An object. of my invention, generally stated, is to provide for controlling the operation of. a reliable and compact contactor in a simple and efiicient manner.

A more specific object of my invention is to provide for obtaining both a time. delay opening of; a contactor in response to normal overloads anda substantially instantaneous opening in re.- sponse tov abnormally high currents.

Another object of my invention is to. provide for, controlling the opening of a. circuit breaker or contactor by; combined thermal and magnetic means.

A further object of my invention is to. utilize a, thermally responsive bimetal tripping. member to. energize a magnetic tripping, means for a circuit breaker or contactor.

Still another object of my invention. is to pro;- vide for readily adjusting the tripping. mechanismof, a contactor.

Other objects. of my invention will be explainedv fully hereinafter.- orwill be apparent. to; those skilled in the art.

In practicing my invention, a main contactoni, a combined. thermal and. magnetic tripping.

means, a control switch and trip, resistors are mounted on a common base. The. operation ofthe contactor may be. manually con-trolled 'by means of a switch. located, remotely from; thez unit;

assembly. Delayed. tripping, on normal. overloads is obtained by means of a- U-shaped t-her-- mally responsive, bimetal which also functions as:

a; one-turncoil to, energize a magnet by'the; load current, thereby obtaining, instantaneous: trips:

ping. on abnormally high currents;

For a better understandingof the nature and-, objects. oi the invention, reference; may" he had to. the following detailed description-, taken. in

conjunction with the accompanying drawings},

cipal features. of. the invention the cover-for:

the unit being, removed;

Fig. 2.-is a view, partly inside elevation; and

partly. in section, of the unitshown in Fig; 1,;

Fig. 3.is.a-view, in section taken alongtheline.

III-.III Of. Fi 1,;

Fig, 4 isaview, in bottom plan,.of the;unit:

shown in Fig. 1;

. member 35.

Fig. 5 is a view,.in section, taken along the line V-V of Fig. 4;.

Fig. 6 is an enlarged detail view, in section, taken'along the line VI-VI of Fig. 4; and

Fig. 7 is a diagrammatic view showing the control'cir-cuitconnections for the contactor and its associated apparatus.

Referring to. the drawings, the structure shown therein comprises an insulating base I" upon which is mounted an electromagnetic contactor H, a. control switch I2 and a. pair of resistors I3. A recess I4 is provided in the bottom side or the base Ill-- in which is mounted a bimetal plate [-5, and an electromagnet I6 having an armature ['12.

As shown most clearly in Fig. 2, a. cover I8 may be attached to the base II] by means of screws=l9which are threaded into brackets 21 on the cover I8. The cover I8protects the contactor I I, the control switch I2 and: the resistors I3.- As shown in Fig. 3, acover plate 22: may be attached tothe bottom of the base Ill to protect the bimetal plate I5, the electromagnet I6' and the: armature I'I.

As shown most clearly in Fig. 3, the contactor II: comprises a U-shaped frame 23, a coil 24, a fixed core 25 which is attached to the frame 23 by a screw 26 and a movable core 2! which is disposed inside ofa sleeve 28 on which the coil is mounted. Contact bars29 and 3| (seeFig.

L) are attached to an insulating member 32 whichin turn, is-a-ttached to one end of the frame 23-by meansof a metal plate 33'EDCITSCIBWSJ34.

A br-idging contact member 35 is disposed to engage contact members 36 and 31 mounted on the contact bars 29 and-31, respectively. An arclug-contact member 38-'is disposed to bridge contact members 39- and 4| also mountedv onthe contact bars 2 9- and 3I,.resp ectively;

As shown most-clearlyin Fig. 3, the bridging contactmember 35and the arcing contact member 38. are carried bythemovable core 21.

insulating member.- 32 andthe bridging contact core 21. A guidebar -is disposed to guide the movement. of the bridging member 35 and the The control: switch: l2. may be: of a standardv construction and isasinglei pole; double throw A. compression-spring 42. isdisposed between the- Another compression spring 43 is disposed betweenthe arcing contact member 38 and a cup washer-44 attached to the end of the-- switch having a snap action with automatic return. The control switch may be attached to the base IE] by means of a U-shaped bracket 46 and screws M. As shown most clearly in Fig. 5, the control switch has an actuating plunger :18 to which is attached an extension cap 49. Terminal members 52 and 53 are provided on the control switch l2 for making the necessary electrical connections.

The resistors i3 are also of a standard construction. Terminal members 5 are provided on the resistors for making electrical connections to the resistors. Main contact studs 55 and 56 are provided for making the main circuit connections to the control unit. Secondary contact studs 51 and 58 are provided for making the control connections to the unit.

As explained hereinbefore, our invention provides for obtaining a time delay operation of the contactor H in response to normal overloads in the circuit controlled by the contactor and an instantaneous tripping characteristic in response to abnormally high currents. The time delay action is of a thermal nature utilizing the bimetal plate l5 which is of a U-shape.

The ends of the U-shaped bimetal are rigidly attached to the base it] by screws 55, and the bimetal is electrically connected in series with the main circuit which is controlled by the contactor I I. The remainder of the bimetal plate i5 is mechanically free and will deflect a certain amount corresponding to the temperature rise in the bimetal, which rise in temperature takes place when there is an increase in the amount of the current flowing in the power circuit and through the bimetal plate. The free end of the bimetal i5 is provided with an adjustable screw 62 which is disposed to engage the lower end of the extension cap 49 on the plunger 38 for the control switch [2.

The instantaneous tripping action is obtained by means of the electromagnet it in combination with the bimetal plate i5. The electromagnet It comprises pole pieces 63 and 6 3 which are attached to the base It) by brackets 55 and 66,

respectively, and a yoke 61 which bridges the polepieces 63 and 64, thereby forming a magnet of a horseshoe type.

As shown in Fig. 4, the pole piece 64 of the magnet is disposed between the two legs of the bimetal plate l5 and is substantially surrounded by the bimetal plate. The other pole piece 63 is at one outside edge of the bimetal plate. Thus, the magnet 16 is energized by the load current flowing in the bimetal plate since this plate functions as a one-turn coil around the pole piece 64 of the magnet. The armature H for the electromagnet l ii is mounted on the opposite side of the bimetal plate i5 and abuts against the two pole pieces 63 and 64' when actuated.

As shown, the armature I! is of a T-shape with the top 68 of the T bridging the pole pieces 63 and 64. The leg 69 of the armature is so mounted in a bracket ll by means of pivot pins 12 that the armature is dynamically balanced. An adjustable screw 13 is provided for adjusting the normal position of the armature H.

A hole M is provided near the end of the leg 69 of the armature. As shown most clearly in Fig. 5, the lower end of the extension cap 49 on the plunger 43 for the control switch l2 extends through the hole 14, and the cap 49 is provided with a flange 15 which is engaged by the leg 69 of the armature. Thus, the plunger 48 of the control switch may be actuated by the armature 4 I! in response to the energization of the magnet H5 or by the bimetal plate [5 in response to the heating of the bimetal by the load current.

As shown in Fig. 6, the armature I1 is so biased by a spring 15 that the armature will not move and operate the control switch until the current through the bimetal is sufficient to overcome the force of the biasing spring H5, as well as a spring Tl (Fig. 7) in the control switch [2. The force of the spring 16 may be adjusted by means of a screw 18 which is threaded through an insert 19 in the base in. The spring it may be adjusted to correspond to a predetermined amount of current, thereby eliminating nuisance tripping by currents below the predetermined amount.

A holding coil 8! is disposed on the pole piece $3 of the electromagnet It. The holding coil 8! is designed to actuate the armature H against the pole pieces 63 and 64 or hold it against the pole pieces once it has been actuated into engagement with the pole pieces by the load current flowing through the bimetal 15 in the manner hereinbefore explained.

As shown in Fig. 7, a switch 82 which is manually operable to open and close its contacts is located remotely from the control unit assembly. The switch 82 is preferably a thermal circuit breaker having a thermally operated tripping mechanism comprising a bimetal 83 which bridges contact members 84 and 85 when a handle is actuated to the closed position. Thus, when a predetermined current flows through the bimetal 83, it is actuated to interrupt the circuit through the contact members and 85.

Referring to Fig. *7, it will be seen that upon bridging the contact members 84 and 85 of the circuit breaker 82, a circuit extends from positive through the contact members 84 and B5, conductor 86, contact members 8'? and '88 of the control switch 2, a conductor 89, the actuating coil 24 of the contactor H and conductor 9| to ground. The energization of the coil 24 closes the contact members of the contactor ii, thereby connecting the bimetal plate H5 in seriescircuit relation with the load circuit which is connected to the terminals 55 and 56.

Upon any fault or overload condition sufficient to actuate the bimetal plate l5 or the armature I! as hereinbefore described, the contact member 81 of the control switch I2 is disengaged from the contact member 88 and engages a contact member 92. This operation of the control switch l2 deenergizes the coil 24 of the contactor ll, thereby opening the circuit through the contact members of the contactor and energizing the holding coil Bl on the electromagnet It. A circuit is also established through the resistors I3.

As explained hereinbefore, the holding coil 8! energizes the electromagnet iii to actuate the armature l1, thereby retaining the contact member 81 of the control switch l2 in engagement with the contact member 92 until the bimetal 83 trips the circuit breaker 82, thereby opening automatically controlled by the overload protective devices, and the reclosing of the contactor is remotely controlled by a manually operable switch or circuit breaker.

From the foregoing description, it is apparent that we have provided both a time delay and an instantaneous tripping scheme for controlling the operation of an electromagnetic contactor. The tripping devices may be readily adjusted to secure the desired operating charactristics, and the apparatus required is light in weight and may be compactly assembled, thereby being advantageous for utilization in aircraft. There is no time lag in the operation of the instantaneous tripping upon abnormal overloads because of the minimum inductance of the one-turn coil provided by the bimetal plate IS. A minimum number of mechanical parts in the system precludes maloperation from friction and other mechanical difiiculties.

Since numerous changes may be made in the above-described construction, and diflerent embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch connected to the operating coil for controlling the energization of said coil, a bimetallic element connected in series in the load circuit to carry the load current, said bimetallic element being disposed to engage the control switch to actuate said switch to efiect deenergization of said coil in response to overload current in the load circuit, and electromagnetic means disposed to independently engage the control switch to effect actuation of the control switch, said electromagnetic means including a magnetic circuit, and the bimetallic element being disposed to at least partially encircle the magnetic circuit, whereby the electromagnetic means is energized by the load current flowing through the bimetallic element.

2. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch connected to the operating coil for controlling the energization of said coil, a bimetallic element connected in series in the load circuit to carry the load current, said bimetallic element being generally U- shaped and being disposed to engage the control switch to actuate said switch to effect deenergization of said coil in response to overload current in the load circuit, and electromagnetic means disposed to independently engage the control switch to effect actuation of the control switch, said electromagnetic means including a magnetic circuit disposed between the legs of the U-shaped bimetallic element to be energized by the current flowing in the bimetallic element, the electromagnetic means being adapted to effect substantially instantaneous actuation of the control switch in response to overload current in excess of a predetermined value in the load circuit.

3. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch connected to the operating coil for controlling the energization of said coil, 2. bimetallic element connected in series in the load circuit to carry the load ourrent, said bimetallic element being generally U shaped and being disposed to engage the control'switch to actuate said switch to effect deenergization of said coil in response to overload current in the load circuit, and electromagnetic means disposed to independently engage the control switch to efiect actuation of the control switch, said electromagnetic means including a magnetic circuit disposed between the legs of the U-shaped bimetallic element to be energized by the current flowing in the bimetallic element, the electromagnetic means being adapted to efifect substantially instantaneous actuation of the control switch in response to overload current in excess of a predetermined value in the load circuit, the electromagnetic means ineluding a holding coil adapted to be energized by actuation of the control switch to maintain the control switch in actuated position.

4. A control device comprising a contactor for controlling a load circuit, said cont-actor having an operatin coil, a control switch connected to the operating coil for controllin the energization of said coil, means for connecting the control switch to an external control conductor to establish an energizing circuit for the coil, a bimetallic element connected in series in the load circuit to carry the load current, said bimetallic element being disposed to engage the control switch to actuate said control switch in response to overload current in the load circuit to cause the control switch to efiecet deenerg ization of said coil, an alternative circuit adapted to be connected to said control conductor, means for completing said alternative circuit when the control switch is actuated, and electromagnetic means for independently effecting actuation of the control switch, said electromagnetic means including a magnetic circuit, and the bimetallic element being disposed to at least partially encircle the magnetic circuit, whereby the electromagnetic means is energized by the current flowing in the load circuit.

5. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch connected to the operatin coil for controlling the energization of said coil, means for connectin the control switch to an external control conductor to establish an energizing circuit for the coil, a bimetallic element connected in series in the load circuit to carry the load current, said bimetallic element being disposed to engage the control switch to actuate said control switch in response to overload current in the load circuit to cause the control switch to eifect deenergization of said coil, an alternative circuit adapted to be connected to said control coductor, means for completing said alternative circuit when the control switch is actuated, and electromagnetic means for independently eifecting actuation of the control switch, said electromagnetic means including a magnetic circuit, and the bimetallic element being disposed to at least partially encircle the magnetic circuit, whereby the electromagnetic means is energized by the current flowing in the load circuit, said electromagnetic means including a holding coil energized from said alternative circuit to maintain the control switch in actuated position.

6. A control device comprising a contactor for controlling a load circuit, said contactor havin an operating coil, a control switch connected to the operating coil for controlling the energization of said coil, means for connecting the control switch to an external control conductor to establish an energizing circuit for the coil, a generally U-shaped bimetallic element connected in series in the load circuit to carry the load current, said bimetallic element being disposed to engage the control switch to effect actuation of said control switch in response to overload current in the load circuit to cause the control switch to effect deenergization of said coil, an alternative circuit adapted to be connected to said control conductor, means for completing said alternative circuit when the control switch is actuated, and electromagnetic means including a magnetic circuit disposed between the legs of the U-shaped bimetallic element to be energized by the load current flowing in the bimetallic element, the electromagnetic means also including a movable armature adapted to independently actuate the control switch in response to overload current in the load circuit in excess of a predetermined value.

3 7. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch connected to the operating coil for controlling the energization of said coil, means for connecting the control switch to an external control conductor to establish an energizing circuit for the coil, a generally U-shaped bimetallic element connected in series in the load circuit to carry the load current, said bimetallic element being disposed to engage the control switch to effect actuation of said control switch in response to overload current in the load circuit to cause the control switch to effect deenergization of said coil, an alternative circuit adapted to be connected to said control conductor, means for completing said alternative circuit when the control switch is actuated, and electromagnetic means including a magnetic circuit disposed between the legs of the U-shaped bimetallic element to be energized by the load current flowing in the bimetallic element, the electromagnetic means also including a movable armature adapted to independently actuate the control switch in response to overload current in the load circuit in excess of a predetermined value, and a holding coil on said magnetic circuit, said holding coil being energized from said alternative circuit to mantain the control switch in actuated position.

HOMER B. JAMES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,761,772 Carpenter June 3, 1930 1,837,761 Crichton Dec. 22, 1931 1,849,280 Chandler Mar. 15, 1932 2,135,829 McGoldrick Nov. 8, 1938 2,307,776 Grant Jan. 12,, 19 43 2,434,186 Wilson Jan. 6, 1948 2,445,110 Gauvreau July 13, 1948 

